Cycles shader colour: values above 1
If you push your color values above 1 your render will become physically inaccurate. You should try to keep your color values at most 1.

Glossy Shader with a color value of 1 1 1 vs 50 50 50

   

Diffuse Shader with a color value of 1 1 1 vs 5 5 5

   

As you can see once you set the color value above one the shader are emitting more light than they are receiving. If you have no light though the scene will not be illuminated by the shaders because the shaders are not actually emitting light they are acting like a multiplier.

You will also notice that in the render output certain pixels have a color value above 1